spaceship design

[beccaelizabeth]

so I'm trying to figure out something about which way is down in a spaceship with no artificial gravity.

If it's sitting there in space spinning then out is down, yes? The spin makes a down.

If it's pushing with big engines then the engine is down, I think. Because it's shoving the floor up at you.

If it's spinning and pushing... does it break? I have no idea. But, does 'down' go diagonal? Depending on how much the engines are pushing.

Because then spaceship corridors being octagons makes logical sense and not just pretty sense.



You know the more I try and write actual SF the more I wish I hadn't given up on my science a level resits. I could have passed. Eventually. Probably.
... Is there a 'science for SF writers' course somewhere? Or a book...
I realise if I only want to write for Doctor Who then science is optional, but, I kind of miss that whole logic and reason thing where you can figure stuff out. It's all very well going 'reverse teh polarity!' and fixing everything, but it's like a whole set of puzzles you can't play with.

Comments

[louiex.livejournal.com]

Ender's Game had an interesting take on internal gravity and directions in space. As strange as the book was sometimes, logistically and with technical stuff like that it was downright fascinating! That's what really kept me reading it now that I think about it...

[beccaelizabeth]

The enemy's door is down.

But Ender's Game uses ultratech gravity control, which my ships I'm trying to visualise don't got.

[47-trek-47.livejournal.com]

Although once it stopped accelerating, the engine would no longer be "down," since the ship and the contents would be moving at the same speed. Out would be down again, if it was spinning. My guess would be the engines would outweigh the spinning during acceleration, so probably everyone would just need to be strapped down for that.

[47-trek-47.livejournal.com]

Oh, and the engines would only need to be on for the initial acceleration up to speed, since there's no friction in space, or for changing directions or slowing down.

[beccaelizabeth]

*nods*
but if running out of fuel wasn't a problem then 'up to speed' wouldn't be, they'd just power all the time and go quick.

[beccaelizabeth]

depends on what acceleration they were using. if they could only do a small push but constantly (ultratech having made up rules) then engines could happen all the time to get places quicker.

[msp-hacker.livejournal.com]

I don't think there is a "down" without gravity. I would refer to things either in, going towards the center of the ship, and out, which is well, out.

But! Since there are Actual Real Life space ships, and they don't have artifical gravity, you can look at pictures of the inside of the ISS or Mir and see what they do. = ) I think it's square/rectangle rooms put inside cylinders.

[beccaelizabeth]

while altered terminology makes sense to people who know they're in space, your average person is just going to experience whichever surface they're pressed towards as 'down'.

Actual Real Life space ships don't have any gravity, spin or ultratech. There was going to be a centrifuge module on the ISS but it got cancelled. So they're not doing what my futuristic space ships is doing.

[melannen.livejournal.com]

Yeah, "down" is the sum of the vectors of the two accelerations, which means the force you feel is in a direction between the two directions, and it's stronger than either of them alone.

(The simplest way to add two 'vectors of force" is visually, by drawing triangles; it's easier to demonstrate with pictures, but basically: draw a line with angle of the angle of force #1 & length representing how strong it is, with an arrow on the to show which way it's pointing; then draw a line for the second force, starting out from the arrow of the first one. Then draw a line connecting the ends of the first two lines to make a triangle, with its arrow on the same end as the arrow of your second line, and that's the direction & strength of the total force you'd feel.)

It's basically the same thing that happens if you're in a spinny thing on Earth, with the downward acceleration of Earth's gravity standing in for the engine thrust (the carnival ride Gravitron is the experience I'm most familiar with; I think they use the same name for it in the UK - if you've never ridden one here's a youtube video of what happens to people inside (http://www.youtube.com/watch?v=7Iy16D-MfnA&feature=related) as the spinniness gets up to speed and the direction & strength of "down" changes.


...I've never found a science for SF writers book that I actually liked much, mostly because they all try to cover far too much to do any of it effectively, but Physics for Poets (http://www.librarything.com/work/82001) was pretty good for basic things like acceleration and general relativity. (It's a college text, but it's not too long, and intended for physics classes for liberal arts majors who don't have much background or talent in math or science, and to teach the sort of physics that might actually come in handy for a poet or a writer or an artist, with (at least in my edition) also stuff put in for a person self-studying, which is what I did.)

[beccaelizabeth]

thanks :)

I like teh spinny fairground rides to watch. I not go on them but they're interesting physics.

that text looks useful. I will look it up.

[zelston.livejournal.com]

Downer of the spinning things for gravity approach is that too fast makes most people messily ill. And too fast turns out to be quite slow. And the smaller diameter of rotation the faster it has to go to get about 1-g. Babylon 5 (the station) was about the right size to be comfortable so any long term use of spinning gravity requires huge vessels. I have/had a spreadsheet somewhere abut this.

With the acceleration method engines are down indeedy. A typical journey would be accelerate towards destination for half the time, turn round, then accelerate away from destination to slow down. All neatly 1-g towards the engines :) If fuel is no problem this is far better than having a honking great big spinny ship!

This site:
http://www.projectrho.com/rocket/
is incredibly useful for keeping sciecne in science fiction :)

[beccaelizabeth]

that site is indeed win.

http://www.artificial-gravity.com/sw/SpinCalc/SpinCalc.htm
is incredibly useful.

And color coded. And if you decide that orange is a perfectly good color things can get smaller.

Somewhere reckons one floor of a building is 3m. So a 9 storey building could spin at 1g with only oranges, but a 4 storey one could only get up to .4g
which I guess is relevant if your 'spaceship' is going to be filmed in a warehouse. Even assuming it's a big donut shape... 50m warehouse anyone?
The Forum is only 60ft / 18m tall.
... if it was half a spaceship it could do .72g before things go red.
... big gap donut work better.

This is fun.

[zelston.livejournal.com]

Ooooh, nifty site! *yoinked*

And handy for so much geekery :D